If you love to read fiction, you must read Await Your Reply by Dan Chaon. If the book was a live performance, at the end the audience would shout, roar, and leap to their feet in applause.
Please don't read a lot of reviews and plot summaries of the book - don't read the customer reviews at Amazon because they tell too much! One of the true delights of this excellent book is simply allowing the author, Dan Chaon, to unfold the story for you. I will tell no more than the book jacket tells: "The lives of three strangers interconnect in unforeseen ways - and with unexpected consequences . . ."
Just pick-up Await Your Reply - a mystery / suspense novel which ponders the nature of identity - and read.
Up-date: NPR review of Await Your Reply